Ep. 81: The Rising Volt Tacklers encounter a Paradox Pokémon disguised as Entei.

81

The Rising Volt Tacklers arrive at the site where Entei was last seen and discuss the possibility of it being one of the Six Heroes. Entei suddenly appears, but its appearance differs from the one they encountered earlier. Liko approaches it with Lucius' belt, but Entei challenges them to a battle by stealing the belt. During the battle, the group realizes that Entei is actually a Paradox Pokémon named Gouging Fire, not the Entei they expected. They manage to gain Gouging Fire's approval, and it joins them. Afterwards, Terapagos and the other five heroes summon the Black Rayquaza. (Source: Wikipedia)